Popular and scholarly histories of computing often focus on technical innovation, and the social impact of those innovations. These histories fail to explain the infrastructure that they must ultimately use as evidence for the success of innovation, as the conduit of its social impact. The story of the US Defense Advanced Research Agency’s (DARPA’s) Arpanet, and the role of both in the invention of the modern Internet, is a central archetype of this genre. Taking our lead from recent work in infrastructure and maintenance studies, we invert Arpanet historiography, by centering our explanation around the infrastructure that is assumed but not explained in innovation-centric accounts. We do so by focusing on the US Defense Communications Agency (DCA), which is traditionally cast, contra DARPA, as a conservative enemy of innovation. We explore DCA maintenance of the Arpanet’s governmental and economic infrastructure—necessary for the Arpanet to function and for the internet to expand—as a first step toward reconfigured histories of network infrastructure.